First of all, there is no such thing as "prompt engineering". Engineering, by definition, is a matter of applying scientific principles to solve practical problems. There are no clear scientific principles here. Writing better prompts is more a matter of heuristics, intuition, and empiricism. And there's nothing wrong with that — it can generate a lot of business value — but don't presume to call it engineering.

Writing better prompts can reduce the frequency of hallucinations but frequent hallucinations still occur even with the latest frontier LLMs regardless of prompt quality.